Sunday, March 2, 2008

According to a report released by the World Health Organization in 2006, it would be feasible to eradicate Chagas’ disease by 2010, using only programs for vector control and existing drugs. These would be good news if their expectations were grounded on sound facts, which they aren’t, as we will see.

Eradicating Chagas’ disease will be an extremely difficult effort which will take a lot of time and indeed, might be impossible. Humans are not the only mammalian host for Trypanosoma cruzi, the parasite that causes the disease. Opossums, rodents, dogs and monkeys can carry the parasite and often do. They live deep in the wild where vector control programs are not applied and roam around areas where humans live too, acting as reservoirs for the parasite. Of course, if there are no vectors it is unlikely that people will get infected and infection rates will be reduced. However, Chagas is foodborne, can be transmitted from an infected mother to her child during pregnancy and through blood transfusions. Testing for Chagas at blood banks is not mandatory in some endemic areas and sometimes, even if mandatory, tests are not enforced in blood banks due to lack of resources.

Eradicating a disease is something completely different than controlling it and the WHO should know better than this over optimistic release. Eradicating is to wipe out completely from the Earth the causing agent of the disease, as happened with smallpox (except for the frozen samples stored in Russia and the US) and probably will happen with Polio (again, except for the stored samples) in a few years, if fundamentalist Muslims does not oppose again to immunization efforts in Africa. As long there are forests, jungles and wild mammals Chagas won’t be eradicated, even if we can apply programs for minimizing new infections and we could work harder on new drugs and a vaccine.

Chagas disease is often linked to misery, filthiness and decay in rural regions. Close contact with animals and primitive housing where the kissing bugs, the vectors, can live comfortably make a deadly combination. The following picture shows an example of such conditions, in San Miguel, a village in the Urdaneta municipality, in Lara State, western Venezuela.

However, with high population mobility, people are not confined anymore to places like this and often emigrate. This has lead to the spread of Chagas disease to countries where it was unknown and vectors do not exist, like Japan, where cases has been reported due to blood transfusions. On the other hand, the change of climate patterns has made possible for the kissing bug and other vectors to move to the North and colonize the southern areas of the US, where there are not only cases of Chagas between immigrants, but also native fauna infected. Screening in blood banks can stop this way of transmission to humans, however, but the infection between animals is a completely different issue.

An example of what the future might bring happened last year in Caracas, in the Chacao municipality, the wealthiest of Venezuela. An outbreak of foodborne Chagas disease affected tenths of persons, in the middle of Caracas, among the richest and most powerful, T. cruzi is alive and well. A terrible tragedy that already has costed lives and mangled several others, with the awful side effects of current therapies, not specific and only effective in early stages of the disease, which often go unnoticed.

This is a lesson for all of us. Life is not a static system, it changes and adapts, it is dynamic, we cannot ignore that fact. To assume that we control all the variables concerning disease transmission is only a delusion and the WHO should be more realistic when making public statements. Declarations like that show that even in at the World Health organization there are widespread ignorance and unrealistic expectations about a health problem that affects to 20 million people, of mostly poor people, with no power or voice, even in the context of their countries. But slowly and surely, that situation is bound to change and Chagas sooner or later will affect more people. We need more funding and different strategies to cope with this problem, before more tragedies occur.